To purify exhaust gas containing air pollutant substances discharged from an engine of a vehicle, an exhaust purifying device may be provided in an exhaust pipe. Furthermore, to reduce noise that occurs during discharge of exhaust gas, a noise-decreasing device (muffler) may be provided in an exhaust pipe. Such an exhaust purifying device and a noise-decreasing device are mounted to a vehicle in an appropriate layout.
An industrial vehicle is provided with a heavy object such as a cargo handling device mounted to the front side of the vehicle, and thus a counter weight is provided on the rear side of the vehicle, to balance the weight of the vehicle in the front-rear direction. The counter weight needs to be large enough to have a sufficient weight, which may considerably affect the layout of the above described exhaust purifying device and noise-decreasing device. Patent Documents 1 and 2 disclose an exemplary layout of an exhaust purifying device and a noise-decreasing device for such type of industrial vehicle.
FIG. 7 is a schematic diagram simply showing a layout of a noise-decreasing device of an industrial vehicle according to Patent Document 1. The vehicle includes an engine 1, a radiator 2 for releasing heat from coolant water flowing through a coolant passage 23 of the engine 1, a counter weight 3 disposed behind the radiator 2, and a muffler 4 for reducing exhaust noise. A blast fan 5 operates in accordance with operation of the engine 1, so that blast from the blast fan 5 passes through the radiator 2, before being discharged outside via a vent 6 having a window shape formed on the counter weight 3. The muffler 4 is shielded by a current plate 7 at the downstream side of the counter weight 3 so as not to interfere with blast from the blast fan 5.
In FIG. 7, the muffler 4 is disposed outside an engine room.
FIG. 8A is a schematic diagram simply showing the first layout of an industrial device including an exhaust purifying device according to Patent Document 2. FIG. 8B is a schematic diagram simply showing the second layout of an industrial vehicle including an exhaust purifying device according to Patent Document 2. In FIGS. 8A and 8B, the same features as those in FIG. 7 are associated with the same reference signs, and not described again.
In the example, a diesel engine is mounted to a vehicle as the engine 1, and a diesel particulate filter (DPF) 8 is provided as an exhaust purifying device, which collects and purifies non-combusted particulate matters (PM) contained in exhaust gas. The DPF 8 performs a regenerating process of combusting accumulated PM by utilizing high-temperature exhaust gas from the engine 1, and thereby maintains its purifying performance. However, if an exhaust pipe 20 between the engine 1 and the DPF 8 is long, the temperature of exhaust gas to be taken into the DPF 8 may decrease.
In the example of FIG. 8A, the DPF 8 is disposed on a lateral side of the radiator 2 to shorten the exhaust pipe 20 between the engine 1 and the DPF 8, thereby ensuring that a sufficient temperature of exhaust gas is taken into the DPF 8, to improve the purifying performance.
Furthermore, it is necessary to perform maintenance to maintain the purifying performance of a DPF including attaching and detaching works by workers, and thus the DPF 8 is disposed on a step of the vehicle in the example of FIG. 8B. Accordingly, the DPF 8 is more accessible for workers, while the length of the exhaust pipe 20 between the engine 1 and the DPF 8 is reduced.
In FIGS. 8A and 8B, dotted lines 14 indicate an engine room that houses the engine 1, and the DPF 8 is disposed outside the engine room 14.